Solution: Suppose that one inner angle of a triangle is X degrees, the other angle is 3X/2, the first angle is 5X/4, and x+3X/2+5x/4 = 180. The solution is that x is 48 degrees, 3x/2 is 72 degrees and 5x/4 is 60 degrees.
If the intersection of the perpendicular lines on both sides of a triangle is on the third side. So this triangle is ()
Solution: right triangle.
Connecting the vertices opposite to the third side, this line divides the triangle into two, and the middle vertical line divides these two into four, respectively proving that the two triangles divided by the middle vertical line are congruent, and one angle of this big triangle is equal to one angle of another triangle that is congruent with him, and so is the other pair. Then the sum of the two angles of a big triangle is equal to the sum of the two angles that are congruent with him, and the two angles that are congruent with him are 180 degrees.
Seventh grade math test questions
(Time 120, *** 100 +5)
1. Choose carefully (if one and only one of the four options in the following questions meets the meaning of the question, fill in the answer code that you think meets the meaning of the question on the answer sheet, with 2 points for each question and 24 points for * * *).
The title is123455678911112.
answer
1. In the figure below, ∠ 1 and ∠2 are opposite to each other:
2. As shown in figure 1, the straight line l 1 and l2 are cut by L, and the following reasoning process is correct:
A. because ∠ 1 and ∠2 are complementary, l 1‖l2.
B if ∠ 2 = ∠ 3, then L 1 ∠ L2.
C. if ∠ 1 = ∠ 2, then l 1 ∠ L2.
D if ∠ 1 = ∠ 3, then l 1 ∠ L2.
3. The four angles formed by the intersection of two straight lines meet one of the following conditions respectively, and the condition that the two straight lines cannot be judged to be perpendicular is:
A, two pairs of vertex angles are equal, and b, a pair of vertex angles are complementary.
C, a pair of adjacent complementary angles is equal to d, and three angles are equal.
4, in the plane rectangular coordinate system, point p (-3, 2005) in:
A. first quadrant B. second quadrant C. third quadrant D. fourth quadrant
5. Given a given point A (2, 1), if the intersection point A is perpendicular to the X axis and the vertical foot is C, the coordinates of point C are
A.2 B.(2，0) C.(0， 1) D.( 1，0)
6. Known points A (- 1, 0), B (1, 1), C (0 0,3), D (- 1, 2), E (0, 1), F.
1。
7. In the plane rectangular coordinate system, line segment A'B' is translated from line segment AB. Assuming that the corresponding point of A'(3-2, 1) is A'(3,4) and the corresponding point of B' (4,0), the coordinates of B are:
A.(9，3) B.(- 1，-3) C.(3，-3) D.(-3，- 1)
8, with the following groups of length of line segments as the edge, can form a triangle is:
A.7cm，5cm， 12cm B.6cm，8cm， 15cm
4 cm long, 6 cm wide, 5 cm high, 8 cm wide, 4 cm high and 3 cm high.
9. As shown in Figure 2, assuming ∠ b = ∠ c, the relationship between ∠ADC and ∠AEB is as follows:
a、∠ADC>∠AEB B、∠ADC